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Resilience features in jBASE 5 upwards

jBASE 5 is a true 64 bit implementation offering non-stop capability in the database. The benefits of the new release include all the advantages that 64 bit runtime will provide, such as those relating to file sizes and memory allocation restrictions. In addition, there are specific features that aid development and non-stop computing.

With non-stop processing abilities available on the application side, it was natural that clients would want to have non-stop abilities embedded as part of the jBASE database too, rather than rely on the hardware failover abilities alone. In order to do this, the following features are being delivered with jBASE 5. They are collectively known as the jBASE Dataguard suite. This collection of technologies allows jBASE to be truly non-stop as a technology platform.

Checkpointing

Enables ‘non-stop’ and ‘known state’ computing—This process periodically pauses activity to enable markers to be set which record the fact that the database is at a known point at that specific time. The recovery modules can refer to these checkpoints to keep the system in a robust state.

Online backup and restore

Allows backups to take place without the need to close down the system—Online backup negates the need for users to be taken offline by backing up the database content while system usage continues. Backup and restore can be performed without the need to shutdown activity on the database server. The backup will be a complete copy of the database at the point in time when the backup process finished. This backup is guaranteed to be in a consistent state because of the Checkpointing feature. The Restore command can also be used on a live system.

jR

Resilient and automatically resizable file system—In badly sized hash files data is frequently split across a number of different frames and all must be read from and written to disk when the data changes. If something goes wrong there is a significant chance that an update will be interrupted and the structure of the file corrupted. In jBASE Release 5, a new resilient file type has been introduced to eliminate this possibility. In a resilient file, where data spans across disk frames, it is built up in a separate area of the file and flushed to disk. Only once it is on disk is a pointer updated to the new data structure rather than the old structure.

As well as being resilient, jR files also resize automatically. This is achieved by separating the location of the data from the record key of the file. This means that the structure of the underlying data can expand without having to redistribute all the data as was the case with previous hash files.

Warm start recovery

The ability to bring a failed system back into play automatically—This feature enables a failed system to be automatically recovered to a known state in the shortest possible time, thereby reducing the length of down-time and the knock on effect on the business. A jBASE 4 database can be recovered by restoring the last backup and replaying the transaction journal but requires manual intervention. Warmstart enables jBASE 5 to automatically recover from events such as power failures in a similar way to mainstream RDBMS products.

jBASE Release 5 Dataguard Guide

This document will describe the features of jBASE which exist in order to protect the database from potential problems which could occur, as well as the methods to use when confronted by each of such circumstances.

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Resilience features in jBASE 5 upwards

Checkpointing

Online backup and restore

jR

Warm start recovery

jBASE Release 5 Dataguard Guide

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